diff --git a/alpine.Dockerfile b/alpine.Dockerfile
index 943999c..4d94e79 100644
--- a/alpine.Dockerfile
+++ b/alpine.Dockerfile
@@ -30,6 +30,9 @@ ENV POSTGRES_DB="**None**" \
     BACKUP_KEEP_MINS=1440 \
     HEALTHCHECK_PORT=8080 \
     WEBHOOK_URL="**None**" \
+    WEBHOOK_ERROR_URL="**None**" \
+    WEBHOOK_PRE_BACKUP_URL="**None**" \
+    WEBHOOK_POST_BACKUP_URL="**None**" \
     WEBHOOK_EXTRA_ARGS=""
 
 COPY hooks /hooks